Swift style syntax

[Andreas Rossberg]

All this is well-known from functional languages, with well-known
solutions. The only real problem is:

let f = (-)

Is this unary or binary `-`?

On 13 October 2015 at 08:06, Isiah Meadows <isiahmeadows at gmail.com> wrote:
> +1 for operators as functions (I frequently is them in languages that have
> them), but there is an ambiguous case that frequently gets me: does `(-)`
> represent subtraction or negation. It's usually the former in languages with
> operators as functions.
>
> But here's a couple other potential syntactical ambiguities, dealing with
> ASI:
>
> ```js
> // Is this `x => f(x)` or `x = (>); f(x)`
> x =>
> f(x)
>
> // Is this `-x` or `-; x`?
> -
> x
> ```
>
> Those can be addressed with a cover production to be used for expression
> statements and direct value assignment, requiring parentheses to clarify the
> latter case in each.
>
> A similar ambiguity problem, arguably harder to resolve, is partially
> applied subtraction, such as `(- 2)`. Is that a -2 or is it equivalent to `x
> => x - 2`? I will caution on this idea, as I know that's the next logical
> step.
>
>
> On Mon, Oct 12, 2015, 06:43 Thomas <thomasjamesfoster at bigpond.com> wrote:
>>
>>
>> Is it possible to extend JavaScript syntax to support Swift style block
>> syntax[1]?
>>
>> In Swift it's possible to omit return keyword
>> ```
>>
>> reversed = names.sort( { s1, s2 in s1 > s2 } )
>>
>> ```
>>
>>
>> As you note below this is already possible in es6, and might I add, has
>> much more intuitive syntax in Es6. The swift syntax looks like a list
>> comprehension gone wrong.
>>
>> or omit argument declaration like this:
>>
>> ```
>>
>> reversed = names.sort( { $0 > $1 } )
>>
>> ```
>>
>>
>> I for one think this is a bad idea - use rest arguments instead. It's
>> pretty terrible as far as readability goes, although I'd like to see more
>> examples of it being used in Swift code.
>>
>> or apply an operator to arguments of a function
>>
>> ```
>>
>> reversed = names.sort(>)
>>
>> ```
>>
>>
>> This might actually be possible - I can't think of any ambiguous
>> situations for passing operators as if they were first class functions. If
>> it is possible, I'd like to see this done.
>>
>> We have the first feature in ES2015 already:
>>
>> ```
>> let sorted = names.sort((a, b)=> a > b);
>> ```
>>
>> But for omitting argument declaration we need to find an alternative to
>> $0, $1... since those are valid variable names in JS. Maybe we can use #0,
>> #1... instead.
>>
>> This is very useful for functional programming aspect of JS. For example
>> in a filter function:
>>
>> ```
>> let passed = objs.filter(#0.passed)
>> ```
>>
>>
>> [1][https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Closures.html]
>>
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